1. Field of the Invention
This invention relates generally to the field of Integrated Services Digital Networks (ISDN) and more particularly to a method and apparatus for implementing communication between devices on a ISDN passive bus without intervention of a central office.
2. Background of the Invention
The evolving ISDN standard proposes use of a passive bus for local connection of a plurality (8) of terminal equipment (TE) devices. These devices are coupled to the ISDN network via a common network terminating device (NT). In the event a D-channel communication path is to be created between devices on the same passive bus, the originating device sends a packet to the central office to set up the call. The central office then sets up a logical channel between the devices to be connected. In this process, the telephone carrier operating the central office becomes involved in the communication process and may therefore charge a fee to the customer for implementing a logical connection between devices on the same passive bus.
The present invention allows TE devices on a common passive bus to avoid such fees by implementing a logical channel independent of the central office. In addition, those skilled in the art will recognize further services that can be provided without intervention of the central office by use of the present invention.
In addition, it is often desirable to provide related and coordinated services between two TE devices such as a personal computer and a telephone. For example, when a sales person receives a telephone call from a client, it would be advantageous for the identity of the caller to be detected by the computer and used to enter a data base which immediately displays customer information to the sales person. Other services dependent upon interaction between TE devices are also advantageously implemented with the present invention.
In European Patent Application No. 151,433, passive bus communication in an ISDN is accomplished by having a network termination unit implement the connections. No particular method or apparatus for implementing passive bus connections is believed to be disclosed in this application.